A. Technical Field
The present invention relates to: a shining coating film formation method which is useful to improve a design property of parts such as automobiles parts and electric appliance parts; and a coated article having an excellent design property which article is obtained by said method.
B. Background Art
To parts such as automobiles parts and electric appliance parts, there is applied a method in which a multilayered metallic coating film is formed on parts comprising plastic materials or metal materials for the purpose of such as providing a metal-tone aesthetic appearance or a metallic tone design and thereby giving a high-quality feeling.
As a method for forming a multilayered metallic coating film, there has so far been known a method by so-called a 3-coat and 1-bake mode or 4-coat and 1-bake mode in which such as a primer coating, a base coat coating, a metallic coating containing a shining material, and a clear coating are sequentially coated to form a multilayer, and then this multilayered coating film is baked at the same time. This method is favorably and commonly adopted in that it is enough that a heating step for curing a coating film is carried out one time. In detail, this method for forming a multilayered metallic coating film by a 3-coat and 1-bake mode or 4-coat and 1-bake mode can be classified into i) a method in which a water base metallic coating is used as a metallic coating for forming an intermediate coating film layer and ii) a method in which a solvent type metallic coating is used as a metallic coating for forming an intermediate coating film layer.
However, as to the aforementioned method i) in which a water base metallic coating is used, although there is an aspect such that a good aesthetic appearance is easy to obtain in that the formed multilayered metallic coating film results in little affinity between layers, yet there is a problem such that: since a water base metallic coating is coated to a surface of an uncured coating film of a base coat coating, the orientation of a shining material may become disordered so as to be insufficient in a metal-tone aesthetic appearance or metallic tone design property. Besides, in the case where the water base coating is used, it is necessary to control the temperature or humidity of coating environment, so that there are disadvantages also in respect to facilities and costs when compared with the aforementioned method in which a solvent type metallic coating is used. Taking these matters into account, the aforementioned method ii) in which a solvent type metallic coating is used is considered as preferable.
As such an art in which a solvent type metallic coating is used, there are known arts in which the step of coating a base coat coating is separated into two steps in which a first base coat coating and a second base coat coating are coated respectively (e.g. refer to patent documents 1 and 2 below). In these prior arts, the brightness is improved by making the amount of solvent larger than usual when the second base coat coating to be coated later is coated. However, even as to this prior art, it is difficult to say that the brightness is sufficiently given.
[Patent Document 1] JP-A-2005-007219
[Patent Document 2] JP-A-2006-150169